Electric plug



Jul 19, 1949.

M. w. 'ROSNER ELECTRIC PLUG Filed April 17, 1948- v NVENTOR BY ATTORNEY Patented July 19,1949

Michael William Rosner, St. Paul, Application April 17, 1948, Serial No. 21,699

This invention relates to electric circuit adapt- I ers or plugs and has particular reference to what are known as male plugs and used in cooperative relation with female or socket plugs for making or breaking the electric; service circuit carried thereby and each of which type of plug carries a pair of spaced contact points or blades for cooperative engagement or disengagement for making or breaking the circuit, respectively.

As is well known these contact blades which materially protrude from the face of the male plug quite frequently fail in ideal frictional union with thefemale blades when a pair of suchplugs are engaged? Thus among the principal objects of the instant invention is to provide simple and practical means for selective adjustment of the protruding portions of the contact blades of the male plugs in relation to those of the female plugs, not only for better conductivity in the circuit, but to provide simple means for temporary holding of the plugs together to prevent accidental breaking of the circuit which so frequently occurs in the common type of plugs.

Other objects and advantages of my specific novel plug will appear as this description proceeds and to which end the figures in the accompanying drawing are as follows:

Fig. 1 is a plan view of the female engaging face of one form of plug embodying the invention.

Fig. 2 is a combined sectional and elevational view on the line 22, Fig. 1.

Fig. 3 is an enlarged perspective view of one of the adjustable contact blades shown in Figs. 1 and 2.

Fig. 4 is a section and elevational view on the line 4-4, Fig. 1, and

Fig. 5 is a side elevational view of a slightly modified form of male plug.

In the drawing, the reference numeral I represents the main body portion of the preferred type of plug and 2 the lesser auxiliary adjustable or grip portion thereof.

The grip portion 2 has formed integral therewith the externally screwthreaded stem portion 3 for axial adjustment within the similarly threaded open bore of the body portion 1 of the plug, said grip portion and stem also having an open through bore 4 for accommodation of the necessary wires carrying the electric current therethrough.

The innermost end of the bore 4 of the stem 3 is tapered outwardly or somewhat frustum shaped as at 5 to provide optional adjustability 3 Claims. (Cl. 173-361) of the outermost extending ends of the opposed contact blades 66 each of which is slightly rockable upon its respective arcuately shaped flat supporting bracket 1 which rest loosely upon the flat marginal face 8 of the larger axial bore of the main body portion I. This loose but firm fulcrum-like connection of the bracket both for its blade holding action and secure wire holding connection, is accomplished by the hole 9 through the bracket 1 being counter-sunk to hold, but slightly loosely, the similarly shaped head of the holding screw bolt Hi, the shank of which is firmly threaded within thebody of the plug as shown in Fig. 4 and the opposite hole ll properly threaded internally for firm holding of the electric Wire holding bolt l2, the surplus shank of which automatically;v extends within the hole IS in the body portion I when assembled and which holes II and i3 register with the holes 9 and l l respectively. In this manner, it is apparent that both bolts [0 and I2 cooperate in forming a firm but slightly rockable fulcrum connection for their respective contact blades 6.

These blades 6 are made preferably of resilient metal and integral each with its respective supporting bracket 1 as clearly shown in Fig. 3 of the drawing with the outer face of the free protruding end thereof serrated transversely as at 14 to improve the holding engagement with the contact points or blades of a cooperative socket plug, not shown, and which may or may not be similarly serrated. The opposite end of each of these adjustable blades is tapered to a somewhat fingerend-like shaped portion for engagement against the wall of and within the frustum-like portion 5 of the stem 3 of the grip or handle portion 2 of the plug so that when such handle portion is screw threadedly adjusted axiallyrthe protruding serrated ends of the blades will be correspondingly adjusted to or from each other, thus providing especially for augmenting of contact of the protruding portions of the blades of a pair of plugs either at the time of initial engagement thereof, or if not at such time, subsequently thereto should, for example, it be desired to temporarily lock the pair of plugs together.

Such temporary locking feature is deemed a very meritorious feature where such plug connections are used in homes or the like where subject to meddling by children.

In the modified form Fig. 5, I have illustrated the main body portion l6 as being of flat disclike form and the grip or adjustable portion l1 carrying the stem l8 of substantially the same diameter as the main body portion l6 which may sertion of one end into a complementary plug, one

end of said blades being adapted to be contacted by said conical indentation on said thumb screw whereby turning said thumb screw inwardly the" ends of the blades contacting said thumb screw will be compressed toward each other and the opposite ends are spread for locking said plug in a complementary plug. 7

2. An electrical plug' comprising a hollow body portion; a sleeve carried axially of said body portion and-at orie endthereof, said sleeve being in a screw threaded engagement with said body portion, said sle'eve beirig provided at one end with an inwardly extendin bevel, spaced contact biades secured'to-said'bddy portion and fulcrumed intermediate their ends thereon for insertion of; one end-into a-complementary plug, one end of said blades being adapted to be contacted by said bevel onsaid sleeve, whereby turning said sleeve inwardly'the" ends" of the blades contacting said sleeve will beconipr'e'sse'd toward each other and the opposite ends will sp'readfor locking said plug in a complementary plug.

3. An electric plu'g comprising an outer body '4 portion having a threaded bore axially at one end thereof; a sleeve screwthreadedly carried in said bore and extending externally thereof, said sleeve having an axial bore therethrough to receive an electrical conductor therethrough, the inner end of said sleeve being beveled in concentrio with said bore, a pair of contact blades rockably secured to said body portion, said blades each comprising a contact portion; a-fingeelike portion extending from said co'ntactportion substantially in alinement therewith, a supporting bracket having a threaded opening adjacent one end and a bore adjacent the opposite end, a screw in said threaded opening to provide a connection for an electrical conductor, said blades being secured to said body portion by means of a screw extending through -the bore in said supporting bracket and into said body portion so as to be rockable on said last mentioned screw, said sleeve portion being threaded into said bore in said body portion so that said finger-like portions engage" said bevel whereby turning said sleeve inwardly' against said finger-like-porti'ons will spread said contact poxtions outwardly. H Q

' MIGHAEL- WILLIAM RGSNER.

REFERENCES orrnn The renewing references are or record in the file of this patent:

UNITED STATES PATENTS I Number Name Date;

1,957,778 Hopkins, Jr May 1934; 1,933,725 Glade, Jr.. Jangzz, i935 2,0999% Mull r Nov, 23; 1937. 2,217,138 

